Travel Health Information Sheets

Prevention of food- and water-borne diseases

Many illnesses, including travellers’ diarrhoea, hepatitis A, typhoid and cholera are contracted through contaminated food and water. Travellers’ diarrhoea is the most common illness contracted abroad, affecting 20% to 60% of overseas travellers.

It can be difficult to avoid contaminated food and water but travellers can take steps to reduce their risk of these diseases by following basic guidelines.

Hands should be washed after visiting the toilet, and always before preparing or eating food. Alcohol gel can be helpful when hand-washing facilities are not available.

Water

Bottled carbonated drinks with an intact seal are usually safe, as are boiled water and hot drinks made with boiled water.

In countries where sanitation is poor it is advisable not to drink tap water or use it to clean teeth unless it has been treated. Ice should also be avoided.

Water can be disinfected by bringing it to a rolling boil [1, 2]. Although boiling is a reliable method of disinfection, it may not always be convenient.

Chemical treatments can be used to disinfect water. However, the effectiveness of these treatments can be reduced by low water temperatures and suspended matter in the water. Travellers should follow the instructions carefully to obtain the best results. Chlorine preparations are usually effective, but protozoan parasites such as Cryptosporidium and Giardia are not always inactivated by these agents [3]. Studies have shown chlorine dioxide to be more effective at inactivating parasites [4]. Using a water filter that has a filter size of ≤0.2 µm to 1.0 µm before using a chemical disinfectant is helpful as water filters can remove suspended matter and parasites if they are functioning correctly.

Following an European Union (EU) directive, iodine is no longer sold or supplied for use in disinfecting drinking water from October, 2009 [1].

Portable, battery-operated devices utilising UV light can also be used to purify water. Water must be free of particulate material before treating. This method may not be practical if large quantities of water need to be disinfected.

Food

Travellers should be advised to choose recently prepared food that is thoroughly cooked and served piping hot.

Certain foods are prone to contamination and should usually be avoided:

Salads (as foods growing close to the ground, such as lettuce, are often contaminated-Uncooked fruits and vegetables, unless they have been washed in safe water and peeled by the traveller)

Fresh or cooked food that has be allowed to stand at room temperature in warm environments, or that has been exposed to flies, such as may happen at open buffets;

Unpasteurised milk, cheese, ice cream and other dairy products ;

Raw or undercooked shellfish;

Food from street traders, unless it is has been recently prepared and is served hot on clean crockery.